stween's build

[Icky]

Is it working yet.. ?
Is it working yet.. ?
Is it working yet.. ?

Nope, you know how it is @exxos so many other things to do

Well this morning I fixed the A14 line to the translator and put in new sockets. The underside had a lot of areas that needed cleaning up. @stween am not sure what solder you are using but it seems to have a thick flux attached to it and the solder looks like there were a few dry joints in a several places.

IMG_2049.jpeg (273.04 KiB) Viewed 1613 times

[stween]

The underside had a lot of areas that needed cleaning up. @stween am not sure what solder you are using but it seems to have a thick flux attached to it and the solder looks like there were a few dry joints in a several places.

Some generic leaded solder. At some point between when I first looked at this board and today, I started playing with separate flux which did leave some gunk, that's probably what you're seeing.

In truth I probably I need a better soldering iron and better eyes

[Icky]

Looking into the DTACK line issue. All chips including the 3V3 <-> 5V translator removed so this is just a straight line with one pull-up

The line reads 1K on the DTACK to 5V which is correct. However it's reading 1K5 on the DTACK to GND which on my other boards is open.

So something odd is going on. I have stripped my H5 back to no chips apart from removing the translators and I get an open connection between GND and 5V on my working board. On stween's board there is 460 ohms. I can not see anything on the board that is untoward so it's going to have to be a remove a chip at a time job. I am going to tackle the 3V3 BUS including the regulator, will remove that and see where we are then.

[exxos]

I think my last suggestion was to remove the regulator to cut power to the 3.3v chips. Then remove the chip DTACK is on for starters. Its the only thing it can be.

Though I don't see how the buffers could have been killed. Unless the regulator is faulty or something. Even if power to the board was reversed or over-volted at some point, likely the DAC / RS232 chips etc would have been killed also.

[Icky]

I think my last suggestion was to remove the regulator to cut power to the 3.3v chips. Then remove the chip DTACK is on for starters. It's the only thing it can be.

Yeah, regulator was next on my list as I had do the translator. With the regulator of the problem still persists.

Though I don't see how the buffers could have been killed. Unless the regulator is faulty or something. Even if power to the board was reversed or over-volted at some point, likely the DAC / RS232 chips etc would have been killed also.

As I said it's going to have to be which chip is the damaged one. I'll start with all the buffer chips just to rule them out.

[exxos]

As I said it's going to have to be which chip is the damaged one. I'll start with all the buffer chips just to rule them out.

3 chips by my last tally but could be more

viewtopic.php?p=95692#p95692

[Icky]

As I said it's going to have to be which chip is the damaged one. I'll start with all the buffer chips just to rule them out.

3 chips by my last tally but could be more

viewtopic.php?p=95692#p95692

All 3V3 / 5V buffers removed as well. Still the same - looking like this is a terminally ill board.

[exxos]

All 3V3 / 5V buffers removed as well. Still the same - looking like this is a terminally ill board.

Send it to me, I'll investigate it.

[Icky]

In fact IPL0, IPL1, IPL2, BERR, VPA, VMA, RESET, HALT, BGACK, BR have 1K4 to GND. Which is odd as for example the IPL0 line doesn't go near any chip on the board just like the DTACK but only has a pull-up resistor.

On my working H5 they are open to GND.

[exxos]

In fact IPL0, IPL1, IPL2, BERR, VPA, VMA, RESET, HALT, BGACK, BR have 1K4 to GND. Which is odd as for example the IPL0 line doesn't go near any chip on the board just like the DTACK but only has a pull-up resistor.

On my working H5 they are open to GND.

Yeah , Ud think if it was a PCB defect, they be shorted to something like GND. There's no pulldowns to 0v so don't get where 1.4k even comes from.

Maybe try running like current limited 10mA on DTACK to gnd and see if it tally's with what 1.4k would actually pull from the 5v rail.I'm not convinced that resistance is real.